An internal bone fixation device is a medical implant used to stabilize, fuse, or distract bones or bone parts. A bone plate used to stabilize a bone fracture is one example of an internal bone fixation device. Traditionally, the fracture site to be plated is exposed through a large surgical incision. This large incision is required to provide sufficient access for manipulation of the plate and associated fastening instrumentation as well as for adequate visualization. It is often desirable to minimize the size of this incision to reduce scarring and soft tissue trauma. However, due to the small surgical incision of these minimally invasive approaches, it is frequently difficult to gain the access required to expose the fracture site, reduce the fracture, insert the bone plate, and maintain the bone plate in the proper position while it is being attached by screws or other means to the bone parts. While it is not always required, an endoscope may be used to enhance visualization.
The repair of a subcondylar mandible fracture illustrates one procedure in which it is desirable to use a minimally invasive approach. The traditional surgical approach involves a large facial incision in an area proximal to the ear. Such an incision can often lead to facial scarring as well as impaired function of the facial nerve controlling the facial muscles. Despite the size of the incision, gaining sufficient access to the fracture site is still difficult. Therefore, this surgical approach is only employed for the most severe condylar fractures.
Some surgeons have performed this procedure using a minimally invasive approach. In this approach, a small intraoral incision is made for the insertion of a bone plate as well as an endoscope for improved visualization. Soft tissue elevation and retraction also occur through this incision. Due to soft tissue constraints, the intraoral incision must be between the upper and lower gum lines.
As the incision site can be several centimeters from the needed location of the bone plate, inserting the bone plate can be difficult. In addition, the axis of access created by the incision is not parallel to the needed axis of the bone, plate, i.e., perpendicular to the fracture. This further complicates insertion and positioning of the bone plate.
Once the fracture has been reduced and the bone plate is in the proper position, the plate must be attached to the bone. Access to the screw holes is usually by a percutaneous incision made over the fracture site. The percutaneous incision is also useful in reducing the fracture with the aid of a trocar or similar device. It is difficult to maintain the position of the bone plate during the drilling and screwing operations used to fix the bone plate. Locating the screw holes through the percutaneous incision can also be problematic. Once the plate is attached, suturing the two incisions completes the procedure.
Another instance where it would be desirable to plate fractures using a minimally invasive approach includes plating of diaphyseal fractures of long bones. For example, a fracture of the tibia may require a plate with a length of 120-130 mm. Traditionally an incision is made of at least this length, whereby if instrumentation existed for distal holding and manipulation of a plate, the plate could be introduced through an incision little more than the width of the plate and fastened through percutaneous incisions.
As the above discussion illustrates, there exists a need for a tool to assist with the implantation of internal bone fixation devices.